Process for sizing textiles and the disposition of sizing wastes therefrom



United States Patent PROCESS; FOR SlZING TEXTILES AND THE DISPO- SITION F SIZING WASTES THEREFROM Harold E. Bode, 8735 N. Olcott, Niles, Ill.

(80 E. Jackson Blvd, Room 2%, Chicago 4, Ill.)

No Drawing. Filed Apr. 28, 1960, Ser. No. 25,481

8 Claims. (Cl. 117-102) a This invention is concerned with a novel method for sizing textile materials, and the disposition of waste products arising therefrom.

In the manufacture of textiles the natural or synthetic fabrics are sized with various agents, such as starch, gelatin, polyvinyl alcohol and the like. -In many casesafter the size has performed its function in some particular phase of textile manufacture or conversion, it is necessary to remove the size before proceeding to the next phase of manufacture or conversion. A major problem then arises as to an economic disposition of the removed size.

As a specific example in the weaving of cloth, it is customary to size the yarn in order to impart the necessary strength and to provide surface protection for the yarn in order to better withstand the mechanical strain of the weaving operation on the loom. After the yarn is woven, however, it is desirable in many cases to remove the size before passing on to the next phases of operation, such as dyeing or printing the cloth, bleaching or other finishing operations. As another example in the printing of textile cloth, it is customary to use a relatively heavy bodied size, such as a thick starch paste, in order to provide a suitable vehicle for the printing dye or pigment so as to perform the operation more effectively. Again, it is desirable in many cases to remove the size after the cloth has been printed in order to improve the hand and color definition of the printed goods.

Starch has been most commonly used in the past for textile sizing, primarily because when modified or processed to suitable fluidity grades, as by acids, enzymes or oxidants, it has done a fairly satisfactory job, is relatively low in cost, easily forms a hydrosol or hydrogel by heating in water, and consequently, may be applied as a size from a water medium. However, many problems have arisen in recent years in textile manufacture that have culminated in the result that the industry has turned more and more to the use of sizing agents other than starch. In general, these are muchmore costly than starch but, on the other hand, their use more or less circumvents the problems that have arisen in the use of starch.

For illustrative purposes, the following may be considered. Conventional starch sizes, e. g., for warp sizing, are not readily or as completely removed as desirable from many textiles after the size has served its function, unless in the desizing treatment the starch is extensively hydrolyzed or otherwise degraded, as by means of enzymes, acids or oxidants. Efiluents from these desizing operations therefore contain sugars, dextrins and other potentially fermentabl-e, putrefiable and biologically oxidizable material which creates a serious problem in the disposition of these wastes. In earlier times these wastes were merely dumped into nearby streams or bodies of water. With the growing public interest against stream polution, many localities have already passed laws to prohibit the sewerage of plant eflluents that have an unusually high biological oxygen demand (B.O.D.). The result recently has been that textile mills, already overburdened with high production costs and low profit margins, have been faced with a choice of providing, at very considerable cost, a sewage disposal plant for their plant eflluents, or changing to the use of relatively costly sizing agents that have a relatively low B.O.D. value.

Among these sizing agents with reasonably low B.O.D. values may he mentioned certain chemical derivatives of starch and of cellulose such as, for example, the hydroxyalkyl others of starch and the carboxymethyl ether of cellulose (CMC). However, experience has shown that to achieve the required low B.O.D. for these and other similar derivatives necessitates carrying the reaction used in making them to the level where the degree of chemical substitution is of the order of about 0.7 to 1.0 substituent group per anhydroglucose unit in the polysaccharide. These products, then, are relatively expensive sizing agents, particularly in relation to the price of cotton goods, not only because of substantial chemical reagent costs, but also because, since cold water solubility of product develops well below this degree of chemical substitution level (0.7 to 1.0), manufacturing procedures, particularly in the case of starch derivatives, must be fundamentally changed to very much more costly processes to cope with the developing water solubility characteristic. Nevertheless, it has apparently been found slightly less costly to use these more recently developed sizing agents in certain operations, e.g., cotton warp sizing, than to build a very expensive sewage disposal plant.

However, use of sizing agents that give low B.O.D. values, although circumventing the immediate limitation imposed :by some present stream pollution laws, does not, obviously, solve the fundamental problem of stream pollution caused by dumping large quantities of organic matter in waste textile mill eflluents into streams or other bodies of water. Accordingly, the invention of a process for textile sizing and size disposal that would overcome the above described disadvantages of prior artmethods, would be a most significant advancement in the art.

It is an object of this invention to provide novel, im-

proved processes for sizing textiles and for the disposal of desizing liquors therefrom.

' It is a more specific object of this invention to provide a novel, improved cotton warp sizing, desizing and desize liquor disposition process, the effluent of which will contribute relatively little, if any, to the pollution load of the mill sewage stream.

Additional objectives will be apparent from a description of this invention which follows:

It has now been discovered in accordance with this invention that when starch is reacted with certain phosphate salts in accordance with certain prescribed procedures, that these starch products, at appropriate fluidity grades, are used, certain surprising textile sizing benefits result. Among those that will be herein considered are the following:

When these particular types of starch compounds are used in cotton warp sizing, it is found that they are so effective that as little as about one-half the weight of size, dry basis, compared to conventional sizing starches, will provide the required yarn strength and protection. This result follows largely from the fact that these starch compounds develop their colloidal properties suitable for cotton warp sizing at a relatively higher viscosity level than do the parent starches which require reduction to conventional fluidity grades. The end result is that since only about one-half the weight of size is required, then on complete desizing of the woven goods only about onehalf the normal weight of size solids appears in the desize liquor. Therefore, the pollution load to sewage is automatically reduced about 50% for processing the same yardage of cotton goods.

The second feature discovered is that these starch compounds not only form hot water soluble products when sizes are prepared from them, but that they also retain their hot water solubility and pasting characteristics even after they have been applied and dried onto the warp. Accordingly, woven cloth may be substantially satisfactorily desized simply by heating in water. The result is that, in the desize liquor, the starch compound appears at substantially the same molecular weight level that it did in the applied size and accordingly, the desize liquor may be reused in some appropriate sizing operation, or even used, in part at least, as make-up liquor for the preparation of subsequent batches of the same type of size, for warp sizing.

A third, and perhaps most significant feature of this invention is that, owing to the chemical nature of the starch compound used for the several types of textile sizing, and because of the fact that the starch compound may be desized from the textile with substantially no degradation of the basic starch molecule, the desize liquor may be readily treated so as to completely recover the starch compound solids dissolved in the liquors by means of a low cost, and novel, precipitation process.

Briefly stated, the novel process of my invention involves the following: Starch is heated in the semi-dry state with an alkali metal phosphate salt to form an alkali metal salt of starch phosphate of relatively low degree of chemical substitution (preferably about 0.02 to about 0.10), and for certain sizing operations, at a viscosity level so that when a size is prepared therefrom, as by gelatinization in water, and this size is applied by orthodox methods, the textile will take up only about one-half of the percentage weight of dry solids that is taken up by conventional sizing starches. After the size has performed its function and is to be removed, desizing is accomplished by essentially a hot water boil ofl, preferably at a pH level slightly above neutrality, e.g., pH 7 to 10, in order to maintain the starch phosphate as its water solu ble alkali metal salt. In instances where reuse of the removed size is impracticable, the desize liquor is treated with material which will supply a cation for neutralizing the negative charge on the anionic starch phosphate polymer, thereby causing its rapid precipitation, when the cation is added in an electro-equivalent proportion. The precipitated starch phosphate solids are removed from the desize liquor, as by centrifuging, filtration or settling, leaving an afiluent with substantially no B.O.D. contributed by the starch size.

Starch phosphates suitable for practicing this invention may be made by a procedure, among others, wherein an intimate mixture of starch and an alkali metal, acid orthophosphate salt is heated in the semi-dry state at about 120 to 175 C. until the desired reaction has taken place. D8. of the product is con-trolled primarily by the ratio of the phosphate salt to starch. The desired fluidity grade may be produced by an independent, conventional procedure, as by acids or enzymes, although in the instant process the desired fluidity grade may readily be obtained directly during phosphating by the proper adjustment of the pH value of the reaction mixture. This is easily accomplished by using predetermined proportions of a mixture of the dihydrogen to the monohydrogen phosphate salt, or even by use of the dihydrogen phosphate salt alone where the highest fluidity grades (lowest viscosity) are to be produced. The monohydrogen phosphate salt may be used alone where substantially no hydrolysis of the starch molecule is desired. Thus for example, for cotton warp sizes and for printing pastes, starch phosphate fluidity grades preferable in accordance with this invention are within the range of to 10, whereas for sizing acetate yarns, for example, fluidity grades of 40 or more are preferable. Fluidity is determined as set forth in Chemistry and Industry of Starch, by R. W. Kerr, published by Academic Press, Inc., New York, 2nd edition, page 133.

All varieties of starch, such as corn, milo, wheat, tapioca and waxy maize, may be used to prepare suitable starch phosphates. However, certain starches are preferable in some specific instances. Thus, for example, tapioca and waxy starches are preferable for cotton warp sizing starch phosphates because of the inherently lesser set-back paste properties of the parent starches, whereas corn and wheat starches are preferable for making starch phosphates for printing paste sizes, because of the inherently shorter paste properties of these parent starches. These inherent properties (which carry through more or less into the phosphate salt derivative) are well known to the art.

In the preparation of sizes from starch phosphates in accordance with this invention, various plasticizers and adjuncts may be added. These may be, for example, water-soluble wax plasticizers for the starch, less soluble yarn lubricants, defoamers, and additives that even more fundamentally change the properties of the size, such as certain resinuous products, as well as additives which are really supplementary sizes, such as carboxymethyl cellulose, locust bean gum and the like. Many of these additives, if not all, are added to sizes prepared from conventional starches.

This invention is more particularly demonstrated by the following examples. However, these examples are intended to be illustrative only, and not limited.

EXAMPLE 1 Preparation of Phosphated Starch A starch suitable for the practice of this invention may be prepared as follows:

240' parts by weight of sodium dihydrogen phosphate hydrate are dissolved in 2040 parts of water at room temperature. Suflicient caustic soda is added to adjust the pH of the phosphate solution to 5.5. Add, with thorough agitation, 1710 parts of waxy maize starch.

Filter thoroughly the resulting phosphate wetted starch and dry the Wet starch cake in a Proctor & Schwartz starch dryer to a moisture content of 10 percent.

Subject the above dry starch .to a temperature of 175 C. for a period of 45 minutes in a continuous belt-type dextrinizer.

This results in the production of a phosphated starch containing 1.0 percent of phosphorus in the form of a phosphate ester group. This phosphated starch will have a fluidity of between about 1 and 5.

In place of a continuous belt-type dextrinizer, one may use a fluid bed heater type dextrinizer wherein the starch is heated while it is air-suspended. In this type of dextrinizer the same product will be obtained by subjecting the starch to a temperature of 175 C. for a period of about fifteen minutes.

EXAMPLE 2 Preparation and Application of a Cotton Warp Size A cot-ton warp size was prepared by heating approximately 100 pounds of a sodium starch phosphate, prepared per Example 1, in 200 gallons of water in about 185-190 F. with vigorous agitation, and then continuing the heating for about 30 minutes. About four pounds of a watersoluble wax, such as Carbowax, was added to the size mix as a plasticizer. At the end, and during the cooking period, sufficient caustic was stirred in to give a finished pH of about 8. A beam of cotton warp ends was sized using a conventional slasher, at a size-box temperature of about 185190 F. and with a squeeze-roll setting so that approximately 7 percent dry substance size was added to the cotton warp. The yarns appeared to be very adequately and uniformly sized, and they separated very much better at the lease-rods than when almost double this weight of a conventional starch size had been applied to this same type of warp.

The sized yarns were woven on a standard loom, but at a reduced Weave-room humidity of percent relative humidity; about percent R.H. is normally used with cotton warps sized with conventional starches. Shedding of the size of the loom was significantly less than normal and weave-room efliciency, with particular reference to ratio of broken ends, was excellent. The woven fabric had a softer, more natural hand and appearance than when sized with a conventional starch size.

A swatch was cut from the bolt of cloth that wasproduced in accordance with procedures givenin Example 2. This swatch was desized under very carefully controlled conditions.

One-half of the swatch was desized by a conventional enzyme desizing process in which the starch component is hydrolyzed to soluble sugars, lower polysaccharides and the like by the amylases present. From these results it was found that the sized cotton cloth contained 3.06 percent starch phosphate size, dry basis.

The second half of the swatch, weighing 18.408 grams, was desized with a hot water wash as follows: The cloth was placed in a glass vessel, 200 cc. of water was added, and the contents of the vessel was stirred. The pH was 7.5. About 0.5 cc. of 0.5 normal sodium hydroxide solution was added, raising the pH value to 10.2, and the vessel was placed in a boiling water-bath for 30 minutes, meanwhile stirring the cloth in the water. When cooled to room temperature, the pH of the desize liquor was found to be 9.2, which is approximately the pH of sodium starch phosphate. The cloth was squeezed through a double-roll wringer and rinsed in 200 cc. of warm water, by stirring therein for about 10 minutes, after which it was again run through the wringer. The swatch was given an additional warm water rinse, wrung out and dried.

The starch phosphate size solids in the desize and first rinse liquors were determined. The desize liquor was found to contain 0.466 gram of starch phosphate size solids and the first rinse, 0.09l gram, or a total of 0.557 gram. Accordingly, since the desized cloth weighed 17.828 grams, the hot water desize process removed 0.5 80/ 17.828, or 3.12 percent, based on dry fabric weight, of starch phosphate size solids. Therefore, hot water desizing completely removed the starch phosphate size. This was confirmed by inspection of the desized swatch.

The remainder of the bolt of cotton cloth was then desized in hot water, using substantially the same procedure as given above, and the cloth was found to be completely desized.

EXAMPLE 4 Reuse of Starch Phosphate Desize Liquor for Additional Sizing Use A portion of the large scale, desize liquor, obtained as described in Example 3, containing approximately 0.3 gram of starch phosphate size solids per 1 00 cc., was used to size-finish a swatch of cotton cloth of the type used for making bed sheets. After immersion in the desize liquor for about 15 seconds at about 45 C., the swatch was squeezed by hand, run through a conventional, double roll wringer, air-dried for about minutes and then ironed with a hand-operated electric iron with the rheostat setting for cotton goods. I The sized and ironed cottoncloth had a very natural appearance, a full-bodied, soft and pliable hand, and showed a stiffness rating equal to a similar swatch that was size-finished with a conventional laundry starch size, sold commercially, using a recommended size concentration of 0.5 gram per 100 cc.

4 EXAMPLE 5 Phosphate Desize Liquor as Make-up for New Warp Size Reuse of Starch ,6 size. Adjustment was made in preparing the new batch of size in using a lesser weight of added sodium starch phosphate, in order to compensate for the starch phosphate already present in the size make-up liquor.

Results on sizing and weaving the cotton warp were quite comparable to the results described in Example 2.

EXAMPLE 6 Warp Sizing Using Several Concentrations of Starch Phosphate Example 2 was repeated several times, varying the sodium starch phosphate concentration in the size, and/or the squeeze-roll setting, so that the warps had size addon values of about 5 percent to about 8 percent, dry

weight basis. In each case the warps wove very satisfactorily and the woven fabrics were completely desized by a hot water desizing wash, as described in Example 3.

EXAMPLE 7 Warp Sizing Using Sodium Starch Phosphate Made From Wheat Starch Example 2 was repeated substantially as described, but with the exception that instead of using a waxy maize starch phosphate that contained about one percent phosphorous ester groups, a wheat starch phosphate was employed that contained about 2 percent phosphorus as phosphate ester groups. The warps with about 7.5 percent size add-on, wove very satisfactorily at 72 percent relative humidity in the weave room. The woven cloth desized substantially completely with a hot water boilolf, and the starch phosphate in the desize liquor was precipitated, using the procedures given in Example 9.

, EXAMPLE 8 Use of Sodium Starch Phosphate in a Printing Paste and Desizing the Printed Fabric A printing paste was made using a wheat starch phosphate, prepared as follows:

A slurry mixture was made of unmodified wheat starch suspended in an aqueous solution of disodium phosphate at about pH 8, and at a concentration sufficient so that when the slurry was filtered and the reaction mixture cake was dried and heated to about 175 C. for about one-half hour, about 0.5 percent phosphorous was combined with the starch as phosphate ester groups. A thick paste was made by heating a 5 percent slurry of the starch phosphate in water, with stirring, to C. and cooling. .This paste was added as thickening agent to a conventional textile printing paste composition and a bolt of cotton calico cloth was printed by orthodox procedures. Color definition and brilliance were rated as excellent.

The printed cloth was desized by agitating in hot water at C. and about pH 8.5 for about 30 minutes, thoroughly rinsing in hot water, passing the desized printed EXAMPLE 9 Precipitation of Starch Phosphate From Desize Liquor by Adding Barium Hydroxide A batch of desize liquor was obtained essentially as described in Example 3. Aliquots of the batch were treated to precipitate the starch phosphate solids dissolved therein as the insoluble barium salt by adding barium hydroxide at three dilferent concentration levels These were 0.25, 0.50 and 1.0 gram of barium hydroxide The centrifugate showed no aesasoe to 100 cc of the desize liquor. After adding the barium hydroxide, mixtures were stirred for about 10 minutes. As the barium hydroxide dissolved, an insoluble floc of the barium starch phosphate formed. On stopping the agitator, the floc rapidly settled to the bottom of the tank, leaving a clear, colorless supernatant liquid. Samples of each supernate were taken for the determination of total dry solids and for an ash determination on these recovered dry solids.

The untreated desize liquor contained 0.27 gram of starch phosphate per 100 cc., on an ash-free basis. At this concentration the several different concentrations of added barium hydroxide precipitated the following percentages of dissolved solids, on an ash-free basis, as

Even at an addition of 0.5 gram of barium hydroxide per 100 cc. of the desize liquor, the treated supernate had substantially no B.O.D.

The above given results also show that the more barium hydroxide added, the greater the percentage of ash-free solids precipitated, although at the order of concentration of dissolved starch phosphate employed in this example, there appears to be no useful purpose served in adding more than about 0.5 gram of barium hydroxide per 100 cc. of desize liquor, which is equal to about 0.75 ounce of barium hydroxide per gallon.

Moreover, the completeness with which starch phosphate is precipitated from desize liquor varies directly at any given barium hydroxide addition, with the concentration of starch phosphate dissolved in the liquor. Thus, for example, when a desize liquor that contained 0.44 gram of starch phosphate per 100 cc., ash-free basis, was treated as described above with 0.5 gram of barium hydroxide per 100 cc., it was found that 72 per cent of the dissolved solids were precipitated, and that to bring this percentage up to the level of 85%, it was necessary to add about 1.0 gram of barium hydroxide per 100 cc. of the desize liquor.

Where desired, excess barium may be removed from the treated desize liquors before sewering by procedures well known to the art, such as, for example, adding an equivalent stoichiometric amount of sodium sulfate, sulfuric acid, or carbon dioxide, centrifuging out the very insoluble barium sulfate or barium carbonate, and discharging the barium free centrifugate.

EXAMPLE 10 Precipitation Starch Phosphate From Desize Liquor by Adding Lime A batch of desize liquor was obtained as described in Example 3, that contained a concentration of 0.29 gram of starch phosphate per 100 cc. To this desize liquor, 1.00 gram of lime were added with vigorous stirring, and stirring was continued for about minutes. On stopping the agitator, the white insoluble floc of calcium starch phosphate that had formed quickly settled. The treated liquor was centrifuged, giving a clear centrifugate. Dry solids and ash determinations on aliquots of the centrifugate showed that all but about 12 percent of the desize liquor solids, on an ash-free basis, had been removed by the lime treatment. The residual treated desize liquor was found to have substantially no B.O.D.

EXAMPLE 11 Precipitation of Starch Phosphate From Desize Liquor by Adding Lead Acetate A batch of desize liquor was obtained as described in Example 2 that contained a concentration of 0.44 gram of starch phosphate per cc. When 0.4 gram of lead acetate trihydrate was added per 100 cc. of this desize liquor, and the mixture was stirred for about 10 minutes and centrifuged, it was found that about 70 percent of the starch phosphate size solids, on an ash-free basis, had been removed, with a corresponding reduction in the B.O.D. of the liquor.

While the herein examples serve to illustrate specific procedures of my invention, numerous factors can be varied without departing from the principles of this invention.

In place of refined starch, any amylaceous material could be used, provided the non-starch impurities do not interfere with the phosphating treatment of the starch or with the precipitating capabilities of the pasted, phosphated, amylaceous matter. In place of calcium, barium, or lead, any cationic metal or organic compound capable of forming a rapidly settling precipitate addition product with dissolved or dispersed phosphated starch, could be used.

My method for solving the stream pollution and B.O.D. problems arising from the use of carbohydrate-treating materials in the processing of manufactured articles, can be applied to industrial liquors other than those obtained in textile processing. Examples are the treatment of cellulose or synthetic fibres, exclusive of textile material; the treatment of aqueously dispersed minerals; and the treatment of stream pollutions containing noncarbohydrate organic compounds. The eificiency of my stream pollution treating procedure will vary with the type of liquor being considered and with the treating conditions. These are subject matters which are being covered in a copending patent application which is a continuation-in-part of the specification of this patent application.

While I have illustrated and described a precise arrangement for carrying the invention into effective use, this is capable of many variations and alterations without departing from the spirit of the invention. I therefore do not wish to be limited by the description of this specification, but desire to avail myself of such changes as may fall within the spirit and scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. A process for sizing, desizing, and desize disposition, comprising: sizing textile fibres with an alkali starch phosphate liquor at a size concentration of sufficient starch content to cause the addition of a substantial amount of the said starch phosphate dry substance to the textile fibre, weaving the said sized fibre into a cloth, desizing the fibre in the said cloth by means of a hot water wash, and precipitating the starch phosphate dissolved in the desize liquor by the addition of a cation-yielding substance that forms an insoluble precipitate with starch phosphate, said alkali starch phosphate containing from about 0.5 to about 2.0 percent of phosphorus as starch phosphate ester groups.

2. The process of claim 1, wherein the cation-yielding substance is lime.

3. The process of claim 1, wherein the cation-yielding substance is an alkaline earth hydroxide.

4. The process of claim 1, wherein the cation-yielding substance is lead acetate.

5. An improved process for textile sizing, desizing and desize disposition comprising: sizing warp yarns with a sodium starch phosphate at a reduced size concentration such that from about 5 percent to about 8 percent, dry weight basis, of the starch phosphate is added to the warp yarns, weaving the said sized yarn into a cloth, de sizing the cloth by means of a hot water wash without significantly degrading the starch phosphate, and precipitating the starch phosphate dissolved in the desize liquor by the addition of a cation yielding substance that 10 forms an insoluble precipitate with starch phosphate, said 8. The process of claim 5, wherein the cationic starch sodium starch phosphate containing from about 1 to about precipitant is an alkaline earth hydroxide. 2 percent of phosphorus as starch phosphate ester groups.

6. A process according to claim 5, wherein the desize References Cited in the file Of this Patent liquor, before cationic precipitation, is re-used as make- 5 UNITED STATES PATENTS up liquor in the preparation of a subsequent batch of I s c p p p size- 2 5 gig 7. The process of claim 6, wherein the cationic starch 412 Neuko 1959 precipitant is an alkaline earth hydroxide, used in sufii- 2961440 Kerr i f g 1960 cient amounts to precipitate substantially all of the starch 10 phosphate. 

1. A PROCESS FOR SIZING, DESIZING, AND DESIZE DISPOSITION, COMPRISING: SIZING TEXTILE FIBERS WITH AN ALKALI STARCH PHOSPHATE LIQUOR AT A SIZE CONCENTRATION OF SUFFICIENT STARCH CONTENT TO CAUSE THE ADDITION OF A SUBSTANTIAL AMOUNT OF THE SAID STARCH PHOSPHATE DRY SUBSTANCE TO THE TEXTILE FIBRE, WEAVING THE SAID SIZE FIBRE INTO A CLOTH, DESIZING THE FIBRE IN THE SAID CLOTH BY MEANS OF A HOT WATER WASH, AND PRECIPITATING THE STARCH PHOSPHATE DISSOLVED IN THE DESIZE LIQUOR BY THE ADDITION OF A CATION-YIELDING SUBSTANCE THAT FORMS AN INSOLUBLE PRECIPITATE WITH STARCH PHOSPHATE, SAID ALKALI STARCH PHOSPHATE CONTAINING FROM ABOUT 0.5 TO ABOUT 2.0 PERCENT OF PHOSPHATE AS STARCH PHOSPHATE ESTER GROUPS. 